As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN THE APU BLEED AIR WAS SELECTED 'ON', THE CABIN FOGGED UP AND SMELLED LIKE OIL. MAINTENANCE REMOVED AND REPLACED THE AIR CYCLE MACHINE. THE APU WAS RUN UP AND THE SYSTEM CHECKED GOOD. NO ODORS OR FUMES NOTED AT THAT TIME AND THE AIRCRAFT WAS THEN RELEASED FOR SERVICE.